Place a metal bowl and a wire whisk or the beaters of a hand mixer in a freezer until well chilled.

In a small saucepan, combine the powdered sugar and cornstarch and whisk to mix well. Slowly whisk in 1/2 cup of the cream until smooth. Place over medium heat and stir constantly to prevent scorching on the bottom until the mixture just begins to thicken and comes almost to a boil. Transfer to a bowl and set aside, stirring occasionally, to cool to room temperature.

In the chilled bowl, combine the remaining 1-1/2 cups cream and the vanilla and beat with the chilled whisk or hand mixer just until the cream begins to hold its shape. While still beating, add the powdered sugar mixture a little at a time and beat just until the mixture forms stiff peaks when the beater is raised and is spreadable; be careful not to overbeat. Use immediately.